This invention relates generally to nut follower devices, and more particularly to nut constructions to reduce or minimize excessive looseness and backlash between a nut and the threads of a screw.
Prior anti-backlash nut constructions have employed a pair of aligned nut bodies disposed end to end which were connected by a spring that biased them in directions either toward or away from one another. By such an arrangement, the one nut body engaged the face on one side of the crest of the thread, with the other body engaging the opposite face of the crest, thereby tending to eliminate looseness between each body and the screw. Various arrangements were employed for retaining the nut bodies in end-to-end relation, such as by confining them in a yoke or housing, connecting them by springs, etc.
The main problems associated with the above constructions was that the efficiency between the screw and nut was low, and precise costly tolerances were required. The spring which biased the two nut bodies together tended to cause binding between each body and the screw, since it was the increased pressures between the latter and each nut body that were being relied upon to reduce the looseness and minimize backlash. Under such circumstances, there was a pronounced tendency for each body to rotate with the screw as the latter turned. Accordingly, special mountings had to be devised to prevent such turning, while still enabling smooth traversing movement of the bodies along the screw axis.
In addition, many of the prior art devices involved large surfaces which were in sliding engagement with one another. As a result there was excessive drag and wear over prolonged periods of use, this leading to erratic operation and consequent down time for effecting periodic maintenance.